What is the working principle of an external motor

What is the working principle of an external motor?
An external motor is a type of electric motor, usually composed of an electromagnet and a rotor. The working principle is that when current passes through an electromagnet, a magnetic field is generated. There is also a magnetic field inside the opposite rotor, and when the two magnetic fields are not consistent, a magnetic force will be generated, causing the rotor to rotate. By changing the direction and magnitude of the current, the rotor can adjust its speed and steering.